In the process of producing a semiconductor device such as IC and LSI, microfabrication by lithography using a photoresist composition has been conventionally performed. Recently, with the increase in integration degree of an integrated circuit, formation of an ultrafine pattern in the sub-micron or quarter-micron region is required. To cope with this requirement, the exposure wavelength also tends to become shorter, for example, from g line to i line or further to KrF excimer laser light. At present, other than the excimer laser light, development of lithography using electron beam, X-ray or EUV light is also proceeding.
The lithography using electron beam, X-ray or EUV light is positioned as a next-generation or next-next-generation pattern formation technology, and a high-sensitivity and high-resolution resist composition is being demanded.
Among others, elevation of the sensitivity is a very important task so as to shorten the wafer processing time, but when higher sensitivity is sought for, the pattern profile or the resolution indicated by the limiting resolution line width is deteriorated, and development of a resist composition satisfying all of these properties at the same time is strongly demanded.
High sensitivity is in a trade-off relationship with high resolution and good pattern profile, and it is very important how to satisfy all of these properties at the same time.
The actinic ray-sensitive or radiation-sensitive resin composition generally includes “a positive type” using a resin sparingly soluble or insoluble in an alkali developer, where the exposed area is solubilized in an alkali developer upon exposure to radiation and a pattern is thereby formed, and “a negative type” using a resin soluble in an alkali developer, where the exposed area is sparingly solubilized or insolubilized in an alkali developer upon exposure to radiation and a pattern is thereby formed.
As the actinic ray-sensitive or radiation-sensitive resin composition suitable for such a lithography process using electron beam, X-ray or EUV light, a chemical amplification positive resist composition utilizing an acid catalytic reaction is mainly studied from the standpoint of elevating the sensitivity, and a chemical amplification positive resist composition using, as the main component, a phenolic resin having a property of being insoluble or sparingly soluble in an alkali developer but becoming soluble in an alkali developer by the action of an acid (hereinafter simply referred to as a “phenolic acid-decomposable resin”), and containing an acid generator is being effectively used.
Also, in order to provide a chemical amplification resist composition remarkably improved in the photosensitive speed by amplifying a photochemical reaction, it is known to use, together with the above-described acid generator, an acid-increasing agent capable of newly generating an acid (for example, a sulfonic acid) by the action of an acid generated from the acid generator (see, for example, JP-A-2011-33729 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)).
On the other hand, in the production of a semiconductor device or the like, patterns having various profiles such as line, trench and hole need to be formed. For meeting the requirement to form patterns having various profiles, not only a positive composition but also a negative actinic ray-sensitive or radiation-sensitive resin composition are under development and, for example, in forming a fine pattern having a line width of 50 nm or less, more improvements are demanded on the reduction of resolution and the pattern profile.
In order to solve this problem, there has been also proposed a method where an acid-decomposable resin is developed using an organic developer other than an alkali developer (see, for example, JP-A-2010-217884).
However, it is demanded to satisfy all of high sensitivity, high resolution and high line width roughness (LWR) performance at a high level, for example, in the fine region where the line width is 50 nm or less.